1. Field of the Invention
The present invention relates to a hydraulic modulator for supplying a hydraulic pressure to a brake device for a wheel.
2. Description of Background Art
A brake device is known which can reduce a pressure in a brake pipe upon operation of ABS (Antilock Brake System), so as to avoid the idle operation of a wheel.
In addition, a brake device is known such that when a brake operating member (lever or pedal) is operated, an input oil pressure according to the operation of the brake operating member is detected and a hydraulic pressure corresponding to this input oil pressure can be generated. See, for example, FIG. 4 of Japanese Patent Laid-open No. 2005-212679.
In Japanese Patent Laid-open No. 2005-212679, FIG. 4 illustrates a hydraulic modulator (6) adapted to be mounted on a motorcycle (the numeral in parentheses is the same as that shown in Japanese Patent Laid-open No. 2005-212679, and the same applies to the other numerals).
In the hydraulic modulator (6), a camshaft (24) is rotatable by a motor (23). A cam roller (25) is provided at a position offset from the center of the camshaft (24), and a piston (16) is in abutment against the cam roller (25). The piston (16) is advanced into or retracted from a hydraulic chamber (17).
When the camshaft (24) is rotated by operating the motor (23) to move the cam roller (25) toward the hydraulic chamber (17), the hydraulic pressure in the hydraulic chamber (17) is increased. Conversely, when the cam roller (25) is moved away from the hydraulic chamber (17), the hydraulic pressure in the hydraulic chamber (17) is reduced.
As shown in FIG. 4 of Japanese Patent Laid-open No. 2005-212679, a master cylinder composed of a cylinder (15), the piston (16), and the hydraulic chamber (17) is integral with the motor (23), so that the hydraulic modulator (6) can be made compact and it is suitable for use in a motorcycle.
However, a space in a motorcycle is extremely limited as compared with that in a four-wheeled vehicle. It is therefore desired to make the hydraulic modulator (6) more compact.